17-(alpha)-hydroxy-20-keto-pregnane compounds and process of preparaing the same



Patented Feb. 13, 1951 1'! (a) HYDROXY COMPOUNDS AND ING THE SAME Lewis Hastings tion of New Jersey 20 KETO PREGNANE PROCESS OF PREPAR- Sarett, Princeton, N. J., minor to Merck & (70., Inc., Ra

hway, N. 1., a corpora- No Drawing. Application October 7, 1947, Serial No. 778,405

7 Claims. (Cl. 260-397.!)

This invention is concerned generally with novel steroid compounds and with processes for preparing them. More particularly, it relates to the preparation of l'l-(a) -hydroxy-20-keto-pregnane compounds from the corresponding 20- keto-pregnane compound and to the intermediate products utilized in preparing the same.

The (a)-hydroxy groupings in the compounds thus obtained, have the same stereochemical configuration as that present in many of the naturally occurring adrenal hormones. This is of special interest in the preparation of pregnene- 4-dioi-17(a),21-trione-3,11,20 (commonly known as Kendall's compound E) and its 21 -acyl derivatives. These compounds are important as adrenal hormones or in therapy requiring adrenal hormone type compounds. They are further useful in the synthesis of similar hormones and compounds.

This application is a continuation-impart of my co-pending application Serial No. 773,525, illed September 11, 1947.

According to the present invention, 20-ketopregnane compounds are treated with hydrogen cyanide or one 01' its salts to produce the corresponding 20-hydroxy-20-cyano-pregnane compound. This product is reacted with a dehydrating agent to produce the corresponding A -20- cyano-pregnene, which is then reacted with an oxidizing agent and the intermediate product hydrolyzed to produce the corresponding 17 (a)- hydroxy-20-keto-pregnane compound. The 1'7- hydroxy group, introduced according to this novel method, is obtained, surprisingly enough, in only one isomeric form, namely the a or "natural configuration.

These reactions may be chemically represented in the case of ZO-keto-pregnane as follows:

CB; H ON .5 I i OH Dehydrating HCN agent e when-pregame zil-hydroxy-zn-cyauo-proznsne For purposes of this application the configuration represented by the notation 17(a) -hydroxy is to be understood to represent the configuration present in the naturally occurring adrenal compounds.

The preferred class of starting materials utilized in practicing the present invention are 20- keto-pregnanes which contain free or esterifled hydroxyl groupings in the molecule, and which may also contain keto groupings. These preferred starting materials may be represented by the following generic formula:

CHIRI wherein R1 and Rs are radicals selected from the class which consists of hydroxy radicals, acyloxy radicals and hydrogen and R: is a radical selected from the class which consists of keto radicals and hydrogen.

Examples 0! this preferred class of starting materials are: 3(a)-hydroxy-11,201diketo-pregnane, 3 acetoxy 11,20 diketo pregnane, 3 benzoxy 11,20 diketo pregnane, 3(a) hydroxy 11,20 diketo 21 hydroxy pregnane, 3(a) hydroxy 11,20 diketo 21 acetoxy pregnane, 30:),21 diacetoxy 11,20 diketo pregnane, and the like.

In carrying out my improved process, I ordinarily react a starting material of the above class CH CH; (L-UN 4l=0 I (i) Oxidising (2) lysis l7( H d O a m-koto-p regmn e A' m-cyano-premm tially assures with hydrogen cyanide, or one of its salts, preterably in solution in a lower aliphatic alcohol. When the resulting 0-20 cyanhydrin contains tree primary or secondary hydroxyl groupings, these may be protec prior to the dehydration reaction, by conversion to the corresponding acyioxy radicals. This is accomplished by reacting said cyanhydrin with an acylatlng agent, such as a lower aliphatic acid anhydride. Alternatively, a secondary hydroxyl group may be protected by oxidation to a ketone, since the 0-20 cyanhydrin grouping is stable to this treatment. It is ordinarily preferred to conduct this oxidation reaction utilizing chromic acid as the oxidizing agent.

The dehydration reaction is best carried out by treating the cyanhydrin, alter acylation or oxidation of any iree hydroxyl groupings which may be present, with a dehydrating agent, such as phosphorus oxychloride. This reaction is ordinarily carried out in solution in a substananhydrous organic solvent, such as pyridine.

The hydroxylation of the resulting A -20- cyano-pregnene compound is ordinarily carried out by treatment with osmium tetroxide, al-

compound is not stable and proceeds, with 10m oi hydrogen cyanide, to the corresponding 1'Ha)- hydroxy-zfl-keto-pregnane derivative.

A preierred teature oi my invention is that 17 (a) -hydroxy-3,20-diketo-pregnane compounds (after acylation or oxidation oi. any auxiliary hydroxyl groupings) can be brominated. and the resulting i-bromo derivative refluxed with pyridine to produce the corresponding M-i'flo) -hydroxy- 3,20-diketo pregnene. It is surprising that the l'i-hydroxy-ZO-keto side chain, which is known to be very sensitive to rearrangement in the presence of acids or bases, is stable to the two reactions Just described.

Moreover, the l'l-hydroxy-zfl-keto-side-chain is also stable to oxidizing agents. This unexpected property makes it possible to react S-hydroxy- 17h) -hydroxy 20 keto-pregnane compounds with oxidizing agents, such as chromic acid, to produce directly the corresponding B-keto- 17in) hydroxy-zfl-keto-pregnane compound.

The following examples illustrate methods of carryin out the present invention, but it is to be understood that these examples are given by way of illustration and not 0! limitation.

Example 1 CB; CH CN CH CN 0 l\ 0H m 0H 0 O HON arm 4 E0 8 (D n s) l POCI;

Pyridine (L-ON One CH: C Ji-O 7=0 O I OH H Pyridine Bromine QI'- though other oxidizing agents, such as aqueous potassium permanganate, hydrogen peroxide in conjunction with a catalytic amount oi osmium tetroxide, and the like, may be employed, ii. desired. When osmium tetroxide is employed, the intermediate osmate ester is conveniently hydroiyaed by treatment with an aqueous solution of sodium sultite. Under these conditions, the intermediate 1730 -dihydroxy -m-eyanopregnane A solution of 1.80 g. 01' 3(a) -hydroxy-i1,20-diketo-pregnane, (compound 1, above), which can be prepared as described by von Euw, Lardon and TD Reichstein in Helv. Chimi Acts. 27, 821 (1944) in a mixture of 25 cc. of alcohol and 6.4 cc. of acetic acid at 0 C. is treated with 6.0 g. 01 potassium cyanide. The solution is allowed to warm to room temperature and after three hours is diluted with TI water and filtered. The wet crude cyanhydrin is dissolved in ethyl acetate and the extract washed with water. Crystallization then gives approximately 1.5 g. of 3(a) -dihydroxy-20-cyano-11- keto-pregnane (compound 2).

To a solution of 1.4 g. of 3(aJBO-dIhYd1'0lW-20- cyano-ll-keto-pregnane in cc. oi acetic acid is added at 16 C. a solution 01 0.9 g. of chromic acid in '7 cc. of acetic acid. At the end of one hour. water is added, the crystalline precipitate filtered and recrystallized from ethyl acetate to produce approximately 0.93 g. of 3,11-diketo-20-hydroxy- ZO-cyano-pregnane (compound 3), dec. C.

About 0.60 cc. oi phosphorus oxychloride is added to a solution containing 2.0 g. 01' 3,11-diketo-20-hydroxy-20-cyano pregnane dissolved in 6.7 cc. of pyridine. Aiter standing at room temperature for 24 hours, the solution is poured into water and dilute hydrochloric acid, extracted with benzene and concentrated to dryness. The crystalline residue consists of nitriles which may be separated chromatographlcally to produce approximately 300 mg. of A "-3,1l-diketo-20-cyan0- pregnene (compound 4) M. P. 222-230 C.

200 ms. of osmium tetroxide and 96 mg. of pyridine are added to a solution containing about 196 mg. or A -3,1l-diketo-20-cyano-pregnene (M.

6 purified by recrystallization from dilute acetone to produce substantially pure material; M. P. 206-206 0.

About 41 mg. or bromine is added to a solution 01' 86 mg. 01 3,11,20-triketo-17h) -hydroxy-pregnane in 1.0 cc. of acetic acid. When the reaction is substantially complete, the solution is immediately poured into water, and the resulting suspension extracted with chloroform. The chloroform extract is washed with water, evaporated to dryness and the residual material crystallized from acetone-ether to produce 4-bromo-3,ll,20- triketo-lflal-hydroxy-pregnane (compound 6).

A solution containing about 71 mg. or 4-bromo- 3,11,20 triketo 17(4) -hydroxy pregnane dissolved in 5 cc. oi pyridine is heated under reflux for approximately 5 hours. The pyridine is then evaporated under reduced pressure, the residue is dissolved in ether and the ether extract is washed with dilute aqueous hydrochloric acid. then with water and is finally concentrated to small volume. The product, which separates, is recrystallized several times from methanol to produce substantially pure A-3,ll,20-triketo- 170:) -hydroxy-prenene (compound 7): M. P. 230-233 C.

trample 2 OHIO Ac CHgOAu CH 0A0 ON ON OHzOAc i i =0 CN O OH OH I 0 O O I P 001: RON G201 yridine -o 0 B0 8 0 0 K l 0) cmoN (1 d-cn KICO; Aqueous l. OsOa 2. Nlsos (I!) OHsOM UHsOAo GH|OA0 CHaOH -O I80 :0 OH H H OH 0 0 0 Acetic I Pyridine Bromine mhydride I oo eo o 0 o I P. 222-230 0.) dissolved in 2 cc. oi bennene. This solution is allowed to stand at room temperature for approximately 19 hours and then diluted with about 10 cc. of alcohol. A solution of 500 mg. of sodium sulfite in 10 cc. of water is added and the resulting mixture is stirred for approximately 15 hours. Most of the alcohol is then evaporated under reduced pressure and the residue is extracted with benzene. The benzene extract is then washed with water and evaporated to dryness. Addition of ether gives crystalline 3,11,20- triketo-l'flul -hydroxy-pregnane (compound 5) M. P. 198-199 C. This compound may be further.

A solution of 2.0 g. of 3 (a) -hydroxy-21-acetoxy- 11,20-diketo-pregnane (compound 8) which can 06 be prepared as described by von Euw, Lardon and 7 to room temperature and after 3 hours is diluted with water. The addition of a large volume of water to the alcohol-hydrogen cyanide mixture precipitates a gum which is extracted with chloroform or ethyl acetate. The extract is 78 washed with water, and evaporated to small A solution of 0.60 g. of chromic acid in 1.2 cc.

of water and 11 cc. of acetic acid is added to a solution containing about 1.2 g. of 3(a),20-dihydroxy-20-cyano-2l-acetoxy-11-keto-pregnane at room temperature. After 1 hour, water is added and the product which precipitates, is filtered and recrystallized from ethyl acetate to produce 3,11- diketo-20-hydroxy-20-cyano-21 acetoxy pregnane (compound 10) dec. 214-217 C.

0.40 cc. of phosphorus oxychloride is added to a solution containing about 950 mg. of 3,11-

diketo--hydroxy-20-cyano-21 acetoxy pregnane dissolved in 3 cc. of pyridine. After standing at room temperature for 24 hours, the solution is poured into water and dilute hydrochloric acid, extracted with benzene and concentrated 20 to dryness. The crude product, after chromatography gives one main constituent, namely A"-3,11-diketo-20-cyano-21 acetoxy pregnene (compound 11) M. P. 189-190 C.

This compound is further identified by hydrolysis to the corresponding Zl-hydroxy derivative, without affecting the cyano grouping. About 150 mg. of the A"-3;l1-diketo-20-cyano-21-acetoxypregnene (compound 11) is dissolved in 5 cc. of

methanol, and a solution containing 200 mg. of

potassium carbonate in 2 cc. of water added thereto. The resulting solution is maintained at approximately 50 C. for fifteen minutes, the methanol is evaporated in vacuo, and the crystalline product, which precipitates, recovered by filtration. Recrystallization of this material from ethyl acetate gives substantially pure A -3,11- diketo-20-cyano-21 hydroxy pregnene (compound 20); M. P. 263-265 C.

CrO;

ono A solution of 1.0 g. of A -3,11-diketo-20-cyano- 21-acetoxy-pregnene in 10 cc. of benzene is treated with 1.0 g. of osmium tetroxide and 0.43 g. of pyridine. After standing at room temperature for 18 hours, the resulting solution is treated successively with cc. of alcohol, and with 50 cc. of water containing 2.5 g. of sodium sulfite. The mixture is stirred for 30 hours, filtered, and the filtrate acidified with 0.5 cc. of acetic acid and concentrated to small volume in vacuo. The

a ueous suspension is then extracted four times with chloroform, the chloroform extracts are combined, washed with water and concentrated to dryness in vacuo. Recrystallization of the residue from acetone gives 3.11.20-triketo-1'H0- 2l-dihydroxy-pregnane (compound 12): M. P. 227-229 C.

This compound is then treated with acetic anhydrlde and pyridine for 15 minutes at room temperature to produce 3,'11,20-triketo-17(c)- hydroxy-2l-acetoxy-pregnane (compound 13); M. P. 222-224 C.

A solution containing 132 mg. of bromine in 1.0 cc. of acetic acid is added to a solution containing 333 mg. of 3,11,20-triketo-1'fle) -hydroxy-21- acetoxy-pregnane dissolved in 5.0 cc. of acetic acid. When the reaction is substantially complete, the solution is immediately poured into water, and the resulting suspension extracted with chloroform. The chloroform extract is washed with water, evaporated to dryness. and the residual material crystallized from acetoneether to produce 4-bromo-3.1'1,20-triketo-1'l'(a)- hydroxy-21-acetoxy-pregnane (compound 14): dec. 190 C.

A solution of 300 mg. of 4-bromo-3,11,20- triketo 17(1) -hydroxy-21-acetoxy-prcgnane in 12 cc. of pyridine is heated for 5 hours under reflux. The pyridine is evaporated in vacuo. the residue is dissolved in chloroform, and the chloroform extract is washed with dilute aqueous hydrochloric acid and with water. The chloroform is evaporated under reduced pressure, and the residual material recrystallized several times from alcohol to produce substantially pure A-3,11,20-triketo-17(c)-hydroxy-21- acetoxy-pregnene (compound 15); M. P. 236- 238 C. (This compound is otherwise designated as Kendall's compound E acetate.)

Example 3 ON on. 0N

on 0 o POCh Pyridine /l. 0s04 I! ZNMSO; CH; CHI

=0 0H 0H 0- o Acetic anhydride 0 Pyridine Aco B (if?) H 21) About 1.70 g. of 3((1)-acetoxy-11,20-diketopregnene (compound 16) which can be prepared as shown by von Euw, Lardon and Reichstein in Helv. Chim. Acta 27, 821 (1944) is dissolved in a mixture of 25 cc. of alcohol and 6.4 cc. of acetic acid and the solution is treated at 0 C. with 6.0 g. of potassium cyanide. The solution is allowed to warm to room temperature and after three hours is diluted with water and the material which precipitates recovered by filtration. 'hc

8,041,100 8( 20 by roxy m te lo a-mfoxy- -cyano-11-ketoanditst-weta.'l'his mtallinemixtu is lmenane (compound 17'), thus obtained, my be dissolved in a solution con aining 3 cc. of purified by recrystallization from ethyl acetate. mine and 3 cc. of acetic anhydride. The re- It decomposes at about 221-223' 0. Yield apsulting mixture is allowed to stand for approxiproximately 90% of theory." mately 3 hours and is then diluted with water To a solution of 293 mg. 01' 3()-acetoxy-20- to produce approximately 850 mg. of crystalline hydron-20-cyano-11-keiopreznane in 1.0 cc. of product; M. P. 200-208" C. Recrystallization or dry pyridine is added 0.10 cc. of phosphorus oxythis material from dilute alcohol gives substanchloride. After standing at room temperature tialLy pure 3(a) -aceto:w-1l()-hydroxy-1i.20- for 24 hours. the solution is poured into water m ikcto-preanane (compound 21); M. P. 208-208 anddilute hydrochloricacid. extracted with ben- 0.: a Anal. calcd for CaHuOs: 0. zone and the benzene extract concentrated to 70.73: H. 0.70. 1"ound: O. 70.83: H. 8.96.

The crystalline residue consists of a The 3(a),17() dihydroiw 11,20 diketo- 3(a)-acetoxy-ll-keto-20-cyano-preanenc. (comlution of 75 mg. of said 8(a).1'l(c)-dihydroxypound 18): M. P. 194-195 C. llzo-diketo-pregnane is dissolved in 0.8 cc. of About 1 70 g of osmium tetroxide and 0.75 cc acetic acid can .2 cc. of water, and the of pyridine are added to a solution con solution is treated with a solution containing about 1.65 g. of A -3 (a) -acetoxy-1l-keto-20- n mg. of chromic acid in 0.06 cc. of water and 1.14 cyano-pregnene dissolved in 10 cc. of benzene.

This solution is allowed to stand at room temperature for 10 minutes. the reaction solution is perature for approximately 20 hours and then diluted with water and extracted twice with treated with a solution of 3.0 g. of sodium sulflte chloroform. The chloroform solution is washed about 5 cc., and said distllland is diluted with lized from ether and recrystallized from dilute about 50 cc. of alcohol. The resulting mixture acetone to produce substantially pure 3,11,20- is stirred at room temperature for about 20 triketo-l'fls) -hydro -pregnane (compound 5): hours, filtered, acidified with a few drops of M. P. 205-200 C.

lmple I HIOAO 0130i 0 0 ON a s (SH: M =0 -0 O O o o miz y c rldn HON i O no no no i H (m H (a) H l. P0 Idin [ma-saw; CHIOAo cmoiin 0111011 J =o c-cN d-cN on i Acetic l. OsO; mhydrlde v c 0 2.011180: 0 Pyridlns 30 H B acetic acid and evaporated to small volume un- 3(a) -hydroxy- 11,20-dilreto-21-acetoxy-pregder reduced pressure. The aqueous mixture is nane (22) is treated with excess pyridine-acetic extracted with chloroform, the chloroform soluanhydride and the mixture warmed on the steam Pregnane (compound 19); M. P. 207408 0.; is added thereto to produce crystals of 300,21- -"=+86.5; Anal. calcd for CnHsaOr: C, diacetoxy-lLzo-diketo-pregnane; (compound 23) 72.39; H, 9.25; found: C. 72.54; H. 9.19. M. P. loo- C., which contain 10% of solvent The product (850 mg.) obtained upon evapooi crystallization. Recrystallization of this maratlon of the mother liquors from the above terial from benzene-petroleum ether gives a preparation consists of a crystalline mixture of product having a dec. point 01' 82-90 0. 300,17) -dlhydroxy 11,20 dlketo-pregnane 76 About 3.0 g. of said 3(c),21-dlacetoxy-11.20-

diketo-precnm is dissolved in a mixture of 80 cc. of alcohol and 11.4 cc. of acetic acid, and the resultinssoiutioniseooiedto 'C.andtreated with about 10.6 c. of potassium cyanide. The mixture is stirred for about one-half hour. and then permitted to warm to room temperature.

the solution is diluted wi precipitate th ohtainedisfllteredandwashed. Thewetcakeis dissolved in ethyl acetate, excess water removed, and the solution is evaporated to sum: zgiume e repregnane: (compmmd 24) M. 1'. with dec.

To a solution of about 2.2 g. of 8(a) .21-diacetoxy-ll-keto-20 hydroxy-20-cyano-pregnane in about 8 cc. of dry pyridine is added approximately 1.2 cc. of phosphorus oxychloride. After standing at room temperature for 24 hours, the reaction solution is poured into water and dilute eluted, employing petroleum ether-ether mixtures, are combined to produce approximately 1.84 g. of crude A-3(a) ,sl-diacetoxy-ll-keto-elicyano-pregnene which is obtained as an oil.

This oil is saponiiled by dissolving in a mixture of 10 cc. of benzene and 10 cc. of 1.1 N methanolic potassium hydroxide. After 10 minutes the solution is acidified with acetic acid. the benzene is evaporated in vacuo. and the residual material crystallized from dilute methanol to produce 1.45 g. of crude product: M. P. 242-254? C. This material is further purified by recrystallization from acetone and from dilute alcohol to produce substantially pure A "-3(e),21-dihydroxy-i1-iretogg-cyano-pregnene; (compound 25) M. P. 258- This product is treated with excess acetic anhydride and pyridine, at room temperature, to produce substantially pure A -3(),21-diacetorwll-ke -20-cyano-prea'nene (compound 28).

To a solution of 1.1 g. of said A "-3(),-iil-diacetoxy-ll-keto-20-cyano-presnene in 11 cc. of dry benzene is added 1.1 g. of osmium tetroxide and 0.50 cc. of pyridine. After standing at room the mixture is treated with 50 cc. of water containins 2.0 g. of sodium sulflte. The resulting mixture is then evaporated in vacuo to a volume of about cc.. and the residual product is diluted with approximately 50 cc. of alcohol. The mixture is stirred at room temperature for 20 hours. filtered, acidified with a few drops acetic acid and evaporated to small volume in vacuo. The aqueous mixture is extracted with chloroform and the chloroform solution is evaporated to dryness in vacuo to produce an amorphous product which presumably consists of a mixture of equal amounts of 3(a),17(a),21- trmwdroxy-llflo-diketo-pregnane and its 3- monoacetate. In addition, the product is contaminated with some green osmium salts. These osmium salts are partially removed by dissolving the product in a small volume of acetone and dilutlns with 100 cc. or absolute ether. The flocculent precipitate is separated and the supersolution is evaporated to dry- The residual material is dissolved in a mixture of 5 cc. of pyridine and ii cc. of acetic anhydride.andtheresultingsolutionisallowedtc 7a with osmium ten-oxide stand at for i The reaction solution is diluted with water and the crystalline material. which precipitates. in recovered by filtration. This product is then recrystallized from dilute acetone and from alcohol to produce 504 mg. of substantially pure 3(a) .21- diacetoxy-l'liei -hydroxy-il,20-dlketo reanane (compound 2'1); M. P. 233-236 0.; [si =+93. (Additional recrystallization from benzene and from acetone-rether failed to raise the meltins point or to rethove a trace of greenmh discoloration from this producti Modifications may be made in carryin out the present invention without departing from the spirit and scope thereof, and the invention is to be limited only by the appended claims.

I claim:

1. The process which comprises treating a A"- zo-cyano-pregnene compound with osmium tetroxide, and hydrolyzing the osmate ester, thus obtained, with aqueous sodium sulflte to produce the corresponding 1''! (a) -hydroxy-20-keto-pregnane compound.

2. The process which comprises reacting osmium tetroxide with a compound of the formula:

OHIBQ wherein R; is a radical selected from the class which consists of keto and hydroxy radicals, and R4 is a radical selected from the class which consists of hydrogen and hydroxy radicals.

3. The process which comprises treating A"- 3,l1-diketo-20-cyano-2l-acetoxy-pregnene with osmium tetroxide, and hydrolyzing the osmate ester, thus obtained, to produce 17(4), zl-dihydroxy-3,ll,20-triketo-pregnane.

4. The process which comprises reacting A"- 3(a) -acetoxy-l1-keto-20-cyano-pregnene with osmium tetroxide and hydrolyaina the osmate ester, thus obtained, with aqueous sodium sulflte to produce 3(a),l'1(a) -dihydroxy-l1,20-diketoprecnane.

5. The process which comprises reacting A".- 3(a),21-diaceton-ll-keto-20-cyano pregncm and hydrolyzing the osmate eater, thus obtained, with aqueous sodium sulflte to produce 3(),17(3,21-trlhydro!y-1l,20- dlketo-pregnane.

8. 3.11.20 triketo 17(11) 21 dlhydroxypreznano.

'1. 3(),17() dlhydroxy 11,20 dlketopregnane.

LEWIS HASTINGS SARE'I'I.

REFERENCES CITED The following references are of record 1n the flle 01' this patent:

. 4 UNITED STATES PATEN'I'B Number Name Date 2,403,883 Relchsteln July 9, 1946 OTHER REFERENCES Euw et a1, Helv. Chim. Auto. 25, mes 988- 1022 (1942).

Kendall, Jour. Biol. Chem. 114, page L111! (1936).

Mason and Kendall. Jour. Biol. Chem. 114, mes 626-627 (1936). 

1. THE PROCESS WHICH COMPRISES TREATING A $1720-CYANO-PREGNENE COMPOUND WITH OSMIUM TETROXIDE, AND HYDROLYZINE THE OSMATE ESTER, THUS OBTAINED, WITH AQUEOUS SODIUM SULFITE TO PRODUCE THE CORRESPONDING 17(A)-HYDROXY-20-KETO-PREGNANE COMPOUND. 